Injection drug use is the general term for any form of drug use that relies on a needle and syringe to introduce a substance into the human body. In addition to strictly drug-related issues like addiction, people who take drugs in this manner have increased odds of developing certain serious or life-threatening infections. In a study published in April 2014 in the journal Addiction, researchers from Australia\u2019s University of New South Wales looked at how a history of childhood physical abuse might impact the chances that any given individual would ultimately become an injection drug user. These researchers concluded that certain levels of childhood abuse have a general impact on drug use risks, but not a direct impact on injection drug use in particular. The Basics Injection drug use is heavily associated with intravenous (IV) drug use. People who take drugs intravenously introduce them directly into the bloodstream through a vein; once inside a vein, a drug will travel rapidly to the brain and produce its characteristic effects. However, some injection users introduce drugs into their bodies more slowly by injecting them under the skin (subcutaneously) or into their muscle tissue (intramuscularly). Substances of abuse that can be introduced by one form of injection or another include heroin (the classic IV drug), methamphetamine, amphetamines, sedative-hypnotic medications and an opioid medication called buprenorphine. Severe and possibly fatal infections associated with IV drug use, in particular, include human immunodeficiency virus (HIV) infection and hepatitis C infection. All injection drug users also expose themselves to risks for abscesses and other forms of potentially severe localized infection. Childhood Physical Abuse The term childhood physical abuse describes the purposeful physical injury of a child by a parent or any other adult. Some children first experience this kind of abuse shortly after being born, while others only experience it at some later point in time. Specific injuries associated with childhood physical abuse include bruises, bites, black eyes, broken bones, lacerations caused by belts or switches, cigarette burns or other types of burns and brain swelling and other forms of brain damage caused by direct or indirect trauma. Unfortunately, the intentional injury of children is a fairly widespread phenomenon throughout the U.S. and the rest of the world. Factors that can contribute to the odds that any particular child will experience physical abuse include having a parent or parents affected by serious drug or alcohol problems, living in a household affected by intimate partner violence (i.e., domestic violence), living in a one-parent household, living in a household affected by poverty and having parents with relatively low levels of educational achievement. Impact on Injection Drug Use In the study published in Addiction, the University of New South Wales researchers used an examination of 300 Australian injection drug users to assess the potential connection between childhood physical abuse and the odds of injecting drugs during adulthood. The researchers used detailed interviews with each participant to gather information on such things as basic exposure to childhood physical abuse, the severity of any childhood physical abuse experienced, involvement in injection drug use, age at first consumption of alcohol, age at first use of illicit\/illegal drugs and simultaneous involvement in more than one form of drug use (known to addiction specialists and public health officials as polydrug use). The researchers found that just over a quarter (25.7 percent) of the study participants had no history of exposure to childhood physical abuse. Thirty-four percent of the participants had a history of exposure to mild or moderate forms of such abuse, while just over 40 percent had a history of exposure to severe forms of childhood physical abuse. After analyzing various factors, the researchers concluded that the participants with a history of severe physical abuse during childhood had unusually high chances of consuming alcohol at a relatively early age and initiating illicit\/illegal drug use at a relatively early age. They also concluded that the participants with histories of any amount of childhood physical abuse had unusually high chances of getting involved in polydrug use. However, the researchers did not conclude that exposure to physical abuse during childhood results in the use of injected drugs at an unusually early age. Significance and Considerations Based on their findings, the authors of the study published in Addiction connect exposure to severe childhood physical abuse with early involvement in alcohol and drug use in general, but not with injection drug use in particular. They also note that, in addition to historic polydrug use, recent polydrug use also occurs more often in people exposed to any amount of physical abuse during childhood. These findings highlight the need for both addicted parents and sufferers of childhood trauma to seek outpatient counseling or alcohol or drug rehab.